The invention relates to improvements in mechanical momentary or alternate action switches. More particularly, the invention relates to improvements in mechanical switches of the type wherein a stressed spring in the switch housing serves to move a contact between first and second positions in one of which the switch is open and in the other of which the switch is closed.
Swiss Pat. No. 650 618 (U.S. Pat. No. 4,398,075) discloses a mechanical switch wherein the stressed spring is mounted for movement in a direction substantially at right angles to a plane halving the angles of pivotability of the contact between its first and second positions. The stressed spring is movable in the plane of pivotability of the contact between its two positions. One end of the stressed spring bears against the contact, and the other end of the stressed spring reacts against a lever. One arm of the lever is pivotably mounted in the housing immediately adjacent a first wall of the housing and another arm of the lever extends substantially diametrically of and across the interior of the housing to a second wall which is located opposite the first wall. The pivot axis for the contact is located between the pivot axis for the lever and the central longitudinal axis of the housing. The switch further comprises an actuator which can pivot the second arm of the lever through the medium of a compensating spring which can be said to constitute a step-down transmission between the actuator and the lever. The actuator can be depressed to thereby stress the compensating spring which pivots the lever against the opposition of a restoring or return spring Since the locus of engagement between the lever and the stressed spring is remote from the pivot axis for the contact, the patented switch exhibits a pronounced switching hysteresis. Moreover, and since the restoring spring opposes the aforementioned compensating spring, the exact distance which the actuator must cover in order to change the position of the contact cannot be determined with a desired degree of accuracy. Still further, the patented switch is relatively long and bulky because the free end of the pivotable contact must be located at a considerable distance (as seen in the axial direction of the housing) from the locus where the stressed spring reacts against the lever.